Regarding audio they say: > Doubling the speed, in our experience, leaves individual words perfectly identifiable — but makes it just about impossible to follow the meaning. Wow, sorry but this is very misinformed. A lot of people me included can listen to audio at 2x. I constantly listen to podcasts (so not a slow narration to begin with) at 2x in English which is not even my native language and I understand everyth…
Two requirements: headphones (you need much more processing power to deal with crappy speakers and poor audio in general) and lack of significant distractions (you can't afford to think about something else). Also, some apps have crappy audio acceleration algorithms. Overcast does it so well that I use it also for listening to audiobooks.
I also think the article is misinformed. You can speed read by regularly training your brain. Just don't expect miracles and don't believe the "experts" who try to sell you miracles.